Homebew subclass - Can I tie the total number of uses of extra (ie non-spell-slot) spells to proficiency bonus?

The idea is that the subclass gets certains spells that they get a one-off use of, ie one casting without using a spell slot, ie using a USE button (this would be in addition to them adding the spell to their spell list as a castable spell).  

The total number of times they can use any of their non-spell-slot versions of these spells is equal to their proficiency bonus. So, with prof= +4, they may have however many spells in their list that they could cast using the USE button instead of the CAST button. But each one would be 'burnt' if they cast it. And, when they'd used this feature a number of times equal to their prof bonus that would burn them all. Until reset on a long rest. 

Is that possible to set up with DnD Homebrew functionality? if so, how?

(FYI, we've tried this mechanic with pen-and-paper and found it works great so am hoping it can be set up to work digitally too.) 

If anyone is a bit of a gun with the homebrew backend, I'd love for some help on this, please and thank you! 

PS I can't share my particular homebrew creation (I think b/c it's based on artificers and includes 2024 spells and apparently that's not yet in creative commons...?). Or something like that. It's not entirely clear to me why. 

Anyhoo, any guidance would be a huge help!  

Thanks. V helpful to understand the limits of the tool. 

Cheers.